1. Field of the Invention
This invention relates to improvements in the construction and assembly of pivotal levers, generally, and to triggers for sprayers, in particular. The trigger of this invention can be integrally molded and includes structural features which permit virtually instantaneous snap-in attachment to a pivot base, such as to the housing of a sprayer, for secure, pivotal attachment.
Pivotal levers have widespread utility in industrial articles of manufacture, for example, as triggers in sprayers. Such levers should be pivotally attached securely to a base, such as, for example, a trigger to a sprayer housing. The design and construction of these levers is in response to a number of competing forces. For example, there is a need for low cost manufacture of the trigger element itself, for low cost trouble free assembly, i.e. attachment of the trigger to a spray head, for smooth operation, once assembled, and for long lasting trouble free operation.
All these considerations must be addressed effectively in order to provide the manufacturer of finished assemblies with a product of truly competitive cost, and the consumer user with a product of economic, completely satisfactory, trouble free construction.
2. Description of the Prior Art
There have been many suggestions for improving the design, construction, and assembly of such levers. For example, the McKinney U.S. Pat. No. 4,161,288 suggests retaining the trigger by providing a spiral chamber in the trigger into which pivot lugs on the sprayer housing can be maneuvered.
The Martin U.S. Pat. Nos. 4,480,768, 4,489,890, and 4,503,998 are sister patents which suggest providing the pivot attachment elements on flexible portions of both the trigger and sprayer housing, so that both of these sets of elements can flex during mating attachment, in order not to excessively damage the pivot lugs, etc. However, both sets of the flexible portions remain flexible, after attachment of the trigger to the sprayer, and these patents leave unresolved, the problem of dislodgement of the pivot lugs from their respective sockets, during forcible pivoting operation of the trigger, due to the flexibility of the lug-carrying portions of the trigger and the sprayer.
The Tada U.S. Pat. No. 4,153,203 suggests providing a lever (trigger) with flexible lateral walls carrying cylindrical pivot lugs, and addresses the problem of disengagement during pivotal operation by teaching to provide rigid "stopper boards" on the body which project from the body to bear against the insides of those flexible portions of the trigger which carry the pivot elements. This is purported to prevent the walls carrying the pivot elements from being thrown inward, thereby preventing unmating of the respective pivot lugs and sockets. This patent is silent, however, as to how, on one hand, the rigid "stopper boards" can, in the same configuration, allow assembly movement or positioning of the trigger unit to bring the pivot lugs into a pre-mating, coaxially aligned orientation with their corresponding sockets on the sprayer housing for mating of these pivotal linking elements without damage, and yet after mating, prevent the movement of these same flexible elements to that same pre-mating, coaxially aligned assembly position which would then allow disengagement of the pivot elements.
There is a need to provide the art with an economical snapin trigger which will provide secure, trouble free operation for the life of the sprayer, and which allows virtually instantaneous attachment to the sprayer housing, either manually or by machine.